Question

Spot the error .why was you absent yesterday

Answer 1

the error is 'was'
the correct sentence is

why were you absent yesterday

Answer 2

Answer: Answer: The given sentence is wrong.

Step-by-step explanation:

As it is an interrogative type of sentence therefore a question mark(?) should be present in the last of the sentence.

In place of "for" "in" should come as it is an appropriate preposition to be used here.

In place of "classes" "class" should come as we are talking about a single class that the student skip yesterday. So correct answer is "Why were you absent in class yesterday?"